Hydraulic ram mechanism



Jan. 5, 1954 F. B. LEVETUS 2,664,860

HYDRAULIC RAM MECHANISM Filed Oct. 16. 1950 1 f "Wu I (3 I I F/G/ 2 "l/e 20 :y l5 ,6 I l /4 Inventor FRA Ncra auvnus Attorney 3 Patented Jan.1954 HYDRAULIC RAM MECHANISM Francis Benjamin Levetus, Allesley,Coventry, England, assignor to The Kcelavite Company Limited, Coventry,England, a company of Great Britain Application October 16, 1950, SerialNo. 190,263

Claims priority, application Great Britain October 17, 1 949 5 Claims.(01. 121-38) This invention relates to hydraulic ram mechanism formoving an operating member against a resisting force, in which theoperating force is applied to the operating member at two points. Theinvention is applicable more particularly but not exclusively toguillotine machines, for instance for cutting stacks of paper sheets, inwhich the cutting force is applied at both ends of the guillotine knife.

According to the present invention hydraulic ram mechanism of the kindspecified comprises a piston and cylinder both of which are movable andto which hydraulic fluid under pressure can be applied in order to movethe piston axially relatively to the cylinder, and two linkages at leastone of which includes a fixed abutment or pivot and which respectivelyconnect the piston and the cylinder to the operating member in such amanner that on the application of hydraulic pressure both linkages tendto move the'operating member in the same direction.

Conveniently, each linkage includes a bell crank lever one arm of whichis connected to the piston or cylinder, as the case may be, while theother arm is connected to the operating member, and these bell cranklevers are oppositely disposed so that movement of the first mentionedarms in opposite directions causes the arms connected to the operatingmember both to move in the same direction. I

It may often be desirable to provide some sort of stop for limiting themovement of the operat ing member, and it is desirable for this stop toprovide a certain cushioning efiect- Thus in one form of the invention ahydraulic stop is provided to limit the movement of each of the linkagesand hence of the operating member.

Where the operating member is a guillotine knife the linkages may act atopposite ends of the knife which may be constrained to move in a desiredpath by means of guide members. Preferably the knife is given a combineddiagonal and rotary movement during its stroke relative to theguillotine base block by means of two nonparallel straight guidesengaged by suitable guide members, at least one of which guide engagingmembers may be adjustable to permit adjustment of the attitude of theknife. By the attitude of the knife is meant the alignment of itscutting edge with respect to the upper surface of the bed which thecutting edge engages at the completion of its cutting movement. In manycases the knife is in its correct attitude at the end of its stroke whenthe cutting edge is exactly parallel with the surface of the bed.

Where there is a stop for limiting the movement of each linkage, eachlinkage preferably includes an adjustable section to permit adjustmentof the end position and attitude of the knife at the end of its stroke.

The invention may be carried into practice in various ways, but oneparticular arrangement intended for use with guillotine machines forcutting sheets of material will be described by.

way of example with reference to the accompanying diagrammatic drawingsin which,

Figure 1 illustrates an arrangement showing the knife of the guillotinein mid-stroke, and

Figure 2 illustrates the same arrangement at the end of the stroke.

In the apparatus shown the guillotine knife I has a straight cuttingedge 2 and moves up and down in a plane perpendicular to the surface'ofthe bed shown at 3. The bed is a block of hard wood sandwiched betweentwo metal plates which lie parallel with the plane of the knife. Inorder to provide the necessary slicing action, the knife is providedwith a pair of inclined guide grooves 4 and 5 in each of which lies aroller 6 and I mounted on a pivot. The slot 5 is inclined atapproximately 45 to the vertical while the slot 6 is inclined at about40 to the vertical and thus as the knife I is moved up or down, theinclined guides impart a combined rotary and diagonal movement to it. Inorder to permit adjustment ofthe attitude of the knife with respect tothe bed, the roller I is mounted on an eccentric 8 which can be rotatedso as to alter the position ofthe roller.

The mechanism for raising and lowering the knife comprises two linkagesconnected to opposite ends of the knife, each linkage beingapproximately a mirror image of the other. Pivoted to brackets 9 and l 0at each end of the knife are approximately vertical thrust arms I I andI2, the lower ends of these arms being ivotallyconnected to bell cranklevers I3 and I4 the pivots I5 and I 6 of which are fixed. The secondarm of the bell crank lever I3 is connected by, a link I1 to a pistonI8, while the second arm of. the other bell crank lever I4 is connectedby another link I9 to a cylinder 20 in which the piston I8 fits. Neitherthe piston I8 nor the-cylinder?!) is rigidly anchored. Means is providedfor ad-' mitting hydraulic fluid under pressure to the ends of thecylinder 20 and for releasingit therefrom in accordance with themovements of a suitable control valve 2I, so that the piston can be madeto move within the cylinder. A 'pipe 22 leading from a suitable sourceof hydraulic pressure is connected to the valve 2|, which is alsoprovided'with two exhaust ports 23 and 24, and two connections 25 and 26to the ends of the ram cylinder 20. Movements of the control spindle 21cause fluid under pressure to be admitted at will to either end of thepiston in a well known manner and it will be appreciated that as thepiston moves along the cylinder, the cylinder will also move axially inthe opposite direction. Thus'the bell crank levers I3 and I4 will beturned about 3 their pivots in opposite directions, so that both thethrust arms H and I2 will move in the same direction, carrying with themthe guillotine knife I.

Since the relative axial positions of .the cylinder 20 and the piston l8are determined solely by the position of the linkages, and since theknife is constrained to move by means of the guide rollers 6 and l in apredetermined path, the system is largely self-adjusting. However, inorder to adjust the depth of penetration of the knife into the bed andalso the attitude of the knife in this position, both linkages areprovided with adjusting devices whose operation will be explained below.The thrust rod ll contains an adjusting device such as a turn-buckle 28while the thrust rod I2 is provided with a telescopic sliding adjustment29.

In order to ensure that the knife only penetrates the bed to apredetermined extent, stops 30 and 3| are provided for arresting themovement of each of the linkages at the ends of the operating stroke. Inorder to overcome the inertia of the moving parts the stops arepreferably hydraulically cushioned, and may be arranged each in itshydraulic cylinder 32 asshown'for the stop .30 in Figure 1 of thedrawings, each cylinder bein connected by means of pipes 33 with thepressure pipe 22 so as to be subject to the same hydraulic pressuresupply as is the operating ram cylinder.

The adjustment .to fix the position of the knife I at the end of itsstroke and its attitude at this position as shown in Figure 2 iseffected as follows:

The telescopic adjuster .25 is first freed for easy sliding andhydraulic pressureis admitted to the right-hand side of the ram cylinder2.0. Owing to the freeing of the adjuster 29 the immediate effect ofapplying'pressure to the cylinder is to rock the lever 14 hard .upagainst the hydraulic stop 3!, and thereafter the piston 18 is moved tothe left under the influence of the hydraulic pressure thereby causingthe "knife to move downwards to the end of its stroke, until the lever13 comes up against its corresponding stop 30. By adjusting theturn-buckle 28 and the eccentric 8 it is then possible to adjust theattitude and position of the knife, since the bracket is still quitefree to move, af:ter which the telescopic adjuster 29 is locked and themechanism is then ready for operation.

What I claim as my invention and desire to secure by Letters Patent is:

1. Hydraulic ram mechanism comprising an elongated operating memberarranged for bodily movement in a plane, means for guiding the movementor said member in said plane, said means being capable of causing saidmember to rotate about an imaginary pivotal axis which is transverse tosaid plane and capable of movement with respect thereto, a floatingcylinder, a piston within the cylinder, .a source .-.of hydraulicpressure and means for connecting the source to the cylinder so astomove the piston and cylinder axially relative to each other, and twolinkages connecting the piston and cylinder respectively to theoperating member at longitudinallyspaced points,'both said linkagesacting on said relative axial movement of said piston and cylinder tomove the operating member substantially in .the same directionand-subject to said guiding means.

.2. Hydraulic ram mechanism as claimed in claim 1, in which the linkagesinclude two bell crank levers one arm of one of which is connected tothe piston while the corresponding arm of the other is connected to thecylinder, the other arms of the said levers being connected to theoperating member, and the levers being mounted in opposed relationshipto cause the arms connected to the operating member both to tend to movesubstantially in the same direction relatively to the operatingmember-upon relative axial movement of said piston and'cylinder.

3. Hydraulic ram mechanism as claimed in claim 2 including at least onehydraulic stop limiting the floating movement of the piston and cylinderand connected mechanism and having its pressure chamber connected to thesource of hydraulic pressure from which hydraulic pressure is deliveredto the cylinder.

4. Hydraulic ram mechanism comprising an elongated operating memberarranged for bodily movement in a plane, guide means for guiding themovement of said member in said plane, said guide means being capable ofcausing said member to rotate about an imaginary pivotal axis which istransverse to said plane and movable with respect to said plane,adjusting means for said guide means to vary the travel of saidimaginary pivotal axis -with respect to said plane, a

floating ram cylinder, a piston within said cylinder, a source ofhydraulic pressure, and means for connecting the source of pressure tothe cylinder so as to move the piston and cylinder axially relative-toeach other, and two linkages connecting the piston and cylinderrespectively to the operating member at longitudinally spaced points,both said linkages acting on said relative axial displacementof saidpiston and cylinder to move the operating member substantially in thesame direction, subject to said guide means.

5. Hydraulic ram mechanism as claimed in claim 4, in which the means forguiding the movement of said operating member comprise two cooperatingguide elements, one of said guide elements comprising a pair ofnon-parallel straight guide members, and the other guide elementcomprising a pair of guide-engaging members, one of said two guideelements being connected to the operating member, while the other guideelement is fixed in relation to said plane; and including means foradjusting the displacement between :the two members of at least one Ofsaid pairs soas to varythe travel of said imaginary pivotal axis.

FRANCIS BENJAMIN LEVETUS.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 178,278 Dooly June 6, 1876 182,994 Dooley .Oct. 10, 1876296,191 Lawlor 1 Apr. 1, 1884 657,452 :Schulz Sept. 4, 1900 1,051,381Berry Jan. 28 1 913 1,556,581 Booth "Oct. 13: 1-925 1,712,786 BosserdetMay 14, 1929 2,223,637 Newkirk Dec. 3 1940 2,306,541 Clay Dec. 29' 19422,320,373 Meyer June 1 1943 2,371,411 Rhodes Mar. '13: 1945 2,441,275Keagle May '11, 1948 FOREIGN PATENTS Number Country Date 955 GreatBritain Apr.'29, 1858 618,399 GreatBritain Feb. 21 1949 284,052 GermanyMay-4: 1915

